(1) Field of the Invention
The present invention relates to a technique for automatically detecting an exact position of the shoulder of a massage recipient or user seated in a massage chair.
(2) Description of the Related Art
There has heretofore been known a massage chair adapted to measure a body shape of a message recipient or user seated therein, just before giving massage to the user using a massaging element, and then perform a massage operation based on the measured body-shape information of the user.
This type of massage chair is designed, for example, as follows. In advance of a massage operation, the massaging element is moved from a waist region toward a head region (from a lower region to an upper region) of a user seating in the massage chair while pressing the massaging element onto the user's back, to measure loads imposed on the massaging element in respective regions of the user. Then, body-shape information of the user is acquired based on the measured loads, and shoulder-position information is acquired based on the acquired body-shape information to detect a should position.
However, if the user adjusts his/her seating position or changes his/her posture during or just after the body-shape measurement, body-shape information or shoulder-position information acquired by the massage chair will likely deviate from an actually body shape or shoulder position of the user.
In view of this problem, the following Patent Publication 1 discloses a massage chair adapted to allow a deviation between an actual body shape or shoulder position of a user and body-shape information or shoulder-position information acquired by the massage chair to be manually adjusted.
Further, the following Patent Publication 1 discloses a massage chair adapted to detect a shoulder position of a user and then re-detect the shoulder position during a massage operation, such as rolling massage.    Patent Publication 1: JP 2003-052780 A    Patent Publication 2: JP 2003-070857 A